1908] GATES—REDUCTION IN OENOTHERA 13 
What significance this early separation of chromosome pairs may 
have is not known, but it appears that the later history of these pairs 
on the spindle can be traced. In the paper just cited (11), the 
writer wrongly identified them with the smaller nucleoli which persist 
by the heterotypic spindle. These chromosome pairs are frequently 
so closely approximated at the end opposite the end of actual connec- 
tion as to give the appearance of a ring. It was thought that these 
tings by condensation (which actually takes place) were reduced to 
the size of these nucleolar bodies. The latter had the size and shape 
of chromosomes, and with a certain depth of stain invariably appeared 
hollow. These pairs are not condensed to rings, however, but to 
chromosome pairs of the ordinary Oenothera type. 
The spirem at this time varies greatly in thickness in different 
parts, exhibiting constrictions and dilatations which indicate more 
or less clearly where segmentation into chromosomes will take place. 
This segmentation may happen while the spirem is still in the con- 
tracted condition (fig. 25), or after it has again uncoiled and distrib- 
uted itself in the nuclear cavity (figs. 24, 26, 28), or before this 
- uncoiling is completed. The segmentation appears to be in some 
cases nearly simultaneous (fig. 24); in other cases the segmentation is 
Successive, as in fig. 23, where.the spirem is clearly divided into three 
portions and the constrictions for the formation of the chromosomes 
are so far advanced that the number of chromosomes to be formed 
by each segment can already be foretold with practical certainty. 
The segmentation at this time is into 14 chromosomes, the sporophyte 
number. A large number of counts made at this time demonstrate 
the absolute constancy of this number in all the individuals of O. 
rubrinervis examined. It is possible, however, that individuals of this 
race may be found whose chromosome number differs from this 
number by one. This matter will be discussed later. 
In every single case where the count could be determined with 
Certainty it was shown to be 14. These counts were all made from 
sections Io thick, and from nuclei which were uncut by the knife. 
The less numerous counts made in the multipolar stage of the hetero- 
typic spindle gave invariably the same number. In this case all in a 
Siven cell were obtained by examining the adjacent sections. In all, 
hundreds of counts were made. In such nuclei as figs. 26, 29, 30, 31 
